Other Comprehensive Income/Loss - Schedule of Information About Amounts Reclassified from Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Gain on sales of securities	$ 0	$ 86
Compensation and benefits	(36,997)	(38,253)
Income before income tax expense	22,511	28,258
Income tax expense	(8,104)	(9,693)
Net income	14,407	18,565
Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Income before income tax expense	(671)	(628)
Income tax expense	271	254
Net income	(400)	(374)
Reclassification adjustment for gain on sales of securities | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Gain on sales of securities	0	86
Reclassification adjustment for net actuarial loss | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Compensation and benefits	(623)	(667)
Reclassification adjustment for prior service cost | Amount Reclassified from Accumulated Other Comprehensive Loss
Amounts reclassified from accumulated other comprehensive loss to the consolidated statements of income
Compensation and benefits	$ (48)	$ (47)